Central nicotinic receptors: vomiting, ear twitching and panting

Area of Science:

• Neuropharmacology
• Autonomic Nervous System Research

Background:

• Nicotinic agonists like nicotine and DMPP can induce physiological responses.
• Understanding the central nervous system pathways involved in these responses is crucial.

Purpose of the Study:

• To compare the effects of intracerebroventricular (ICV) nicotine and DMPP on vomiting, ear twitching, and panting in cats.
• To elucidate the receptor mechanisms underlying these drug-induced responses.

Main Methods:

• Administered nicotine and DMPP ICV to unanesthetized cats.
• Utilized nicotinic (hexamethonium) and muscarinic (atropine) blockers.
• Investigated responses in cats with area postrema ablations.

Main Results:

• Nicotine produced stronger overall effects than DMPP, though DMPP's vomiting and ear twitching were longer-lasting.
• Hexamethonium abolished nicotine- and DMPP-induced vomiting and ear twitching.
• Atropine did not block vomiting or ear twitching but affected panting.
• Area postrema ablation prevented vomiting but not ear twitching or panting.

Conclusions:

• ICV nicotine and DMPP induce vomiting and ear twitching through central nicotinic receptors.
• Panting is mediated by acetylcholine mimicking action on receptors with mixed nicotinic and muscarinic properties.